Electric motors and relays employing electro-magnetism generated in a coil as the motive force have been well known for a number of years. Such devices invariably comprise a moving element and a stationary element on at least one of which is provided a coil through which electrical current is passed to create an electro-magnetic field which acts on another coil, a magnet, or a ferrous member provided on the other of the two elements to provide a motive force by which relative movement between the two elements is effected.
As is well known, such motors have functioned well in a nearly infinite variety applications since their inception, however they do suffer certain drawbacks a few of which are set out below.
In the case of an analogue watch, for example, if an electro-magnetic motor is employed to drive the clock mechanism, strong outside magnetic fields can have an adverse effect on the accuracy of the clock mechanism. What is more, because of the requirement in such motors of a coil having an adequate number of turns to provide an electro-magnetic field of a desired strength in response to the passage of electrical current therethrough, it is impossible to make them smaller than the minimum size of such a coil, thus making it difficult to reduce the size and thickness of the watch.